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Magnetisation and Electron Spin Resonance of the colossal magnetoresistive La0.67Ca0.33Mn1-x FexO3

Zając T., Folcik L., Chmist J., Kołodziejczyk A., Drulis H., Krop K., Gritzner G.

Materials Science Poland

2006

Vol. 24, No. 3

795--801

We report magnetisation and electron spin resonance (ESR) measurements on colossal magnetoresistive manganites La0.67Ca0.33Mn1-x FexO3 with x = 0, 0.01, 0.03, 0.06, 0.10 and 0.15 in the vicinity of the magnetic (TC) and metal- insulator (TMI) transition temperatures. Above TC the resonance lines with g?2 are caused by the ferromagnetic metallic clusters exhibiting the double exchange interaction between Mn3+-Mn4+ ions. The lines were observed with cooling far below both TC and TMI and were fitted by Dysonian line-shape. Temperature dependences of the linewidths exhibited a minimum value at Tmin?1.25 TC followed by an increase of the width with further cooling toward TC. The anomalous behaviour of the line-width below Tmin is due to an appearance of a ferromagnetic metallic phase within the paramagnetic matrix. The role of phase segregation in which the compounds are phase - separated into a mixture of ferromagnetic and paramagnetic regions is discussed.

The hydrogenation process of the Gd3Ni compound

Tristan N. V., Palewski T., Drulis H., Folcik L., Nikitin S. A.

Materials Science

2003

Vol. 21, No. 3

357-361

Reaction of intermetallic Gd3Ni with hydrogen and transformation of the crystal structure depending on hydrogen concentration is investigated. It is shown that Gd3Ni belongs to the group of intermetallic compounds which are thermodynamically unstable during hydrogenation and undergo a decomposition into the rare earth hydride and the transition metal. Nickel plays a role of the catalyst in the reaction and supports the formation of GdH3 at low temperatures.